Method for manufacturing a base for the envelope of an electric component

ABSTRACT

A method of manufacturing a base for the envelope of an electric component, for example a semiconductor device, in which a pressure member is provided on one side in the cavity of a jig, which cavity has an approximately rectangular cross-section, after which a member of insulating material which softens upon heating is placed on the pressure member from the other side where a chamber of a larger cross-section is present which communicates with the cavity, after which of a conductor grid the conductors of which are supported at one end by a strip and are bent at their other end transverse to the plane of the grid the ends connected to the strip are inserted into a narrow slot between the pressure member and the wall of the cavity until the bent ends of the conductors bear on the insulating member after which the chamber is closed by a closure plate, the jig is heated and a force is exerted via the pressure member, in which the bent ends of the conductors are forced against the closure plate by the insulating member and a part of the softened insulating material is forced between the conductors in the direction of the side walls of the chambers so that a base is formed the bent ends of which of the conductors are situated on the upper side of the insulating member and the parts of the conductors connected thereto with are embedded in the insulating material and the further part of the conductor project from the lower side of the insulating member.

United States Patent [1 1 Friebel et a1.

[ Dec. 25, 1973 METHOD FOR MANUFACTURING A BASE FOR THE ENVELOPE OF ANELECTRIC COMPONENT [75] Inventors: Hendrikus Johannes ChristianusFriebel, Nijmegen; Simon Jonker, Emmasingel, Eindhoven; GerardusCornelis Marie Benschop, Nijmegen, all of Netherlands [73] Assignee:U.S. Philips Corporation, New

York, NY.

[22] Filed: Dec. 23, 1971 [21] Appl. No; 211,277

[30] Foreign Application Priority Data Primary Examiner-Charles W.Lanham Assistant Examiner.loseph A. Walkowski Atrorney-Frank R. Trifari[57] ABSTRACT A method of manufacturing a base for the envelope of anelectric component, for example a semiconductor device, in which apressure member is provided on one side in the cavity of a jig, whichcavity has an approximately rectangular cross-section, after which amember of insulating material which softens upon heating is placed onthe pressure member from the other side where a chamber of a largercross-section is present which communicates with the cavity, after whichof a conductor grid the conductors of which are supported at one end bya strip and are bent at their other end transverse to the plane of thegrid the ends connected to the strip are inserted into a narrow slotbetween the pressure member and the wall of the cavity until the bentends of the conductors bear on the insulating member after which thechamber is closed by a closure plate, the jig is heatedand a force isexerted via the pressure member, in which the bent ends of theconductors are forced against the closure plate by the insulating memberand a part of the softened insulating material is forced between theconductors in the direction of the side walls of the chambers so that abase is formed the bent ends of which of the conductors are situated onthe upper side of the insulating member and the parts of the conductorsconnected thereto with are embedded in the insulating material and thefurther part of the conductor project from the lower side of theinsulating member.

6 Claims, 10 Drawing Figures PAIENI 050251915 SHEETZIIFS IV ENT RHENDRIKUS J.CH.FRIE BEL O S SIMON JONKER BY GERARDUS C.M.BENSCHOP METHODFOR MANUFACTURING A BASE FOR THE ENVELOPE OF AN ELECTRIC COMPONENT Theinvention relates to a method of manufacturing a base for the envelopeand an electric component, for example a semiconductor device.

There are known various methods of manufacturing a base for asemiconductor device, for example an integrated circuit or a thin filmor thick film circuit, in which a flat grid of metal conductors is used.According to a known method, the grid is clamped between a lower partand an upper part of a jig, while a preshaped glass member is providedin a cavity of the jig. After heating the jig, the glass member isforced in the shape determined by the cavity. The flat conductorsproject from the side walls of the thus shaped base. So in this base, nometal base cap which surrounds the side walls can be used so that thebase maybe vulnerable.

Semiconductor bases are also known having a circular cross-section inwhich a glass insulating member is incorporated in a metal base cap andthrough which a number of conductor wires are passed. During themanufacture pre-shaped glass insulating members are used which areprovided with apertures through which the conductor wires are passed.The conductor wires are fixed mutually by means of apertures present ina matrix. The heated glass in the matrix cavity adheres to the metalbase cap and the conductor wires are sealed simultaneously. Conductorsincorporated in a grid cannot be used.

it is the object of the invention to provide a method of manufacturing abase for an electric component, for example a semi-conductor device,which has a flat and box-shaped construction, which has only smalldimensions and in which a grid of conductors can be used which projectsfrom the lower side of the base. The method according to the inventionis characterized in that a pressure member is provided in a mould havinga cavity of approximately rectangular cross-section, which pressuremember closes the cavity on one side for the greater part, after which amember of an insulating material which softens upon heating is placed onthe pressure member from the other side where a chamber of a largercross-section is present which communicates with the cavity, that aconductor grid is used the conductors of which are supported at one endby a strip and are bent transverse to the plane of the grid at theirother end, the ends connected to the strip being inserted into a narrowslot between the pressure member and the wall of the cavity and the bentends of the conductors bearing on the insulating member, the chamberbeing then closed by a closure plate, the mould being heated and a forcebeing exerted via the pressure member, so that the bent ends of theconductors are forced against the closure plate by the insulating memberand a part of the softened insulating member is forced between theconductors in the direction of the side walls of the chamber so as toform a base with the bent ends of the conductors situated on the upperside of the insulating member, the parts of the conductors connectedthereto embedded in the insulating member and the further part of theconductors projecting from the lower side of the insulating member.

In a preferred embodiment of the method according to the invention ametal base cap which is open on the lower and upper sides is placed inthe chamber after providing the grid of conductors and the upper side ofthe base cap is closed by the closure plate, the part of the softenedinsulating member forced between the conductors moving in the directionof the wall of the base cap and a hermetic connection being formedbetween the base cap and the insulating member. By the use of a metalbase cap, a mechanically rigid base is obtained, The upper side of thebase cap may be shaped so that the connection of a lid by means of awelding operation can simply be carried out, there being sufficientspace for the welding electrodes.

The member of insulating material used preferably is a crystallised ornon-crystallised glass.

The conductors are preferably incorporated in a grid comprising arectangular frame in which two oppositely located sides of the frameconstitute the strips which support two series of conductors presentinside the frame, the grid being bent to approximately U-shape so thatrows of conductors are formed which coincide with the limbs of the U andthe bent ends coincide with the connection member of the limbs of the U.

With this method it is possible to simultaneously manufacture a numberof bases in a mould. For that purpose a mould is used having a number ofaligned cavities and use is made of a series of conductor grids whichare connected together and which are constituted by one strip of metal,the connection place of adjacent frames of the series being situated inthe part of the frames which coincides with the connection member of thelimbs of the U, centering apertures being present in said parts of theframes for centering the grids in the mould.

The invention also relates to a device for the series production ofbases for electric components, for example semiconductor devices.According to the invention, such a device is characterized in that it isconstructed from a sealing block, a closure plate and pressure members,the sealing block comprising a number of rows of mainly rectangularcavities which at one end have a chamber of a larger cross-section, thesealing block being closable on the side of the chambers by the closureplate and the pressure members being introduced into the cavities on theoppositely located side, each cavity being bounded on one side by twospaced-apart upright dams extending in the direction of the width of themould and on the other side by upright ridges present between the damsand forming part of cross beams, a clearance which exists between thepressure members introduced into the cavities and the dams of the matrixcavities having a value which exceeds the thickness of the grid ofconductors to be used only to a slight extent. The structure of such amould is comparatively simple. As a result of the small clearancebetween the-dams and the pressure members where the grid of conductorsis to be located, a larger resistance prevails at that area against thepenetration of material of the insulating member so that the conductorsare not covered with said material at said area.

According to one embodiment, longitudinal slots and transverse slotsextending at right angles thereto are present in the sealing block, thedams being constituted by upright parts situtated between thelongitudinal and transverse slots, the cross beams being secured in thetransverse slots in such manner that the ridges constitute a boundary inthe longitudinal slots, the sealing block comprising apertures in whichthe pressure members are movable.

According to another embodiment, the sealing block is constructed frominterconnected continuous longitudinal and cross beams, said continuouslongitudinal beams being arranged at mutually equal distances andcomprising equally spaced recesses on the side of the closure plates inwhich the cross beams fit in such manner that the upright ridges aresituated between two continuous longitudinal beams, the width of theridges being smaller than the distance between the longitudinal beams toobtain a slot for receiving the conductor grid.

The invention also relates to a base for the envelope of an electriccomponent, for example, a semiconductor device, in which the base has abox-shaped construction and comprises flat electric conductors which areformed from a grid of conductors. According to the invention, such abase is characterized in that the side walls consist of a metal base capwhich is closed at one end by an insulating member and comprises at itsother end a projecting edge which forms a connection part for a lid, theflat current conductors comprising at one end a portion which is benttransverse to their longitudinal direction and which is situated on theupper side of the insulating member, the conductors being passed furtherthrough the insulating member and projecting therefrom on the lowerside.

The flat conductors are preferably situtated in two rows, the bent endsof the conductors of the two rows facing each other.

In order that the invention may be readily carried into effect, a fewexamples thereof will now be described in greater detail, by way ofexample, with reference to the accompanying drawings, in which FIG. 1shows diagrammatically the filled mould FIG. 2 shows diagrammaticallythe parts with which the mould is filled FIG. 3 shows diagrammaticallythe formation of the base FIGS. 4 to 6 are a cross-sectional view, aplan view and a longitudinal sectional view, respectively, of apreferred embodiment of the base according to the inventron FIG. 7 showsa grid of conductors to be used for the base FIG. 8 is a perspectiveelevation of a part of a mould in the fillling position FIG. 9 is asectional view of a part of the mould FIG. 10 is a perspective view of apart of another mould.

FIGS. 1, 2 and 3 show by way of example the manufacture of a base whichhas proved to be particularly suitable for a hermetic envelope of asemiconductor device. A sealing block 1 comprises a cavity 2 ofapproximately rectangular cross-section which opens into a chamber 3having a larger cross-section. On a pressure member 4 provided in thematrix cavity 2 a moulding 5 of, for example, sintered glass is placed(see FIGS. 1 and 2). The moulding comprises a recess 6 in which a metalplate 7 is laid which serves to secure a semiconductor crystalafterwards. In the narrow slots between the wall of the cavity 2 and thepressure member 4 flat conductors 8 formed from a metal strip areinserted. FIG. 2 shows diagrammatically said conductors incorporated ina grid. A connection strip 9 connects the conductors at one end. Theother ends 10 are bent and bear on the moulding 5. FIG. 2 shows one oftwo separate rows of conductors 8 which are each connected to a strip 9.It is also possible, for example, to incorporate all the conductors in aframe as is shown in FIG. 7. A

base cap 1 l is then placed in the chamber 3 after which the cavity isclosed by a closure plate 12. FIG. 2 is a diagrammatic perspectiveelevation of the pressure member 11, the moulding 5, the plate 7, theconductor grid 8, 9, 10 and the base cap 11.

After filling the mould, it is turned upside down as is shown in FIG. 3,the pressure member 4 is loaded, for example by a weight, and the mouldis placed in a furnace. The glass moulding 5 is softened as a result ofthe temperature prevailing in the furnace. The loaded pressure member 4exerts pressure on the moulding as a result of which on the one hand thebent ends 10 of the conductors and the plate 7 tightly pressed againstthe closing plate 12 and on the other hand a part of the softenedmoulding is forced between the conductors into the chamber 3. Themoulding 5 has such a thickness that the whole chamber 3 is filled, aglass insulating member adhering to the base cap 11 being formed and theconductors being embedded therein. The upper side of the bent parts 10of the conductors remain uncovered as well as the upper side of theplate 7 sealed in the insulating member. Especially as a result of theconductors projecting from the lower side of the base, sufficient spaceis available for the welding electrodes so that it is possible to weld alid to the base cap. This welding is very favourable.

The slot distance between the pressure member and the wall of the matrixcavity is maintained so small that the insulating material of thesoftened moulding 5 during pressure is not forced upwards in the slotsand, consequently, does not cover the conductors at that area. Thereforeno measures need be taken to seal the space between the conductors whichare present in the slot, so that the jig can structurally be simple andno restrictions are imposed upon the shape of the conductors.

It is not necessary to use the metal base cap 11. As a material for theinsulating member is to be considered first of all a crystallized ornon-crystallized glass. Other materials, however, for example asynthetic resin, may also be used. are

FIGS. 4 to 6 show an embodiment of a base for a hermetically sealedsemi-conductor device which is particularly favourable to manufacture. Aglass insulating member 16 through which conductors 17 are passed ispresent in a metal base cap 15. The ends 18 of the conductors in thisembodiment are embedded in the upper side of the insulating member 16;the other ends project from the lower side of the base and arepreferably at a standarized distance to secure them in apertures of amounting panel. If necessary, the conductors 17 may be bent for thispurpose as is denoted in broken lines. A recess 19 is present in theupper side of the insulating member 16. A metal plate 20 is incorporatedin said recess. A semiconductor element can be secured to the plate 20.Contact places on the semiconductor element may be connected, forexample by means of gold wires, to the ends 18 of the conductors 17.However, it is also possible to connect the semiconductor elementdirectly to the conductors by means of the direct contact method. Inthat case the plate 20 may be omitted. The conductor ends 18 must ofcourse be situated in the correct pattern for direct contact connection.The upper side of the base cap 15 is provided with a flared flange 22. Ametal cover can be secured to said flange 22 in a simple manner,preferably be welded, in which a qualitatively very good hermeticenvelope is obtained. Welding the lid to the base cap presents greatadvantages over other connection methods, for example soldering. Thewelding connection can be carried out very rapidly, the cost ofmanufacture is low and the semiconductor element remains cold duringwelding. As a result of the conductor projecting on the lower side ofthe base and by providing the flange it is possible to weld in a simpleconventional manner, heat evolution occurring only at the area of theflange and the lid. Instead of a flared flange on the base cap, the lidmay be provided with the same effect with a flange projecting to theupper side. If desirable, any other connection method for the lid may ofcourse also be used.

FIG. 7 is a slightly diagrammatic example of the conductors for a baseshown in FIGS. 4 to 6 which conductors are incorporated in a grid 24.The conductors 17 are, for example, etched or punched from a metal stripand during the manufacture of the base they remain connected to a frame23 and thus maintain their mutual desirable positions. The grid 24 isbent along the line a-a to a U-shape and in that shape it is sealed inthe insulating member during the manufacture of the base. When the baseis ready, the superfluous frame is removed by clipping the conductorsalong the lines b-b. When several bases are manufactured simultaneouslyin a matrix, grids are preferably used which are united by means of aconnection member 25. This connection member is situated between thelines a-a. An aperture 26 for centring the grids in the mould may bepresent in the connection member. Such an embodiment has the importantadvantage that the grid is flexible so that during the sealing of theinsulating member the differences in expansion between the grid and thematrix can easily be compensated for.

The base described with reference to FIGS. 4 to 6 may have a differentconstruction at various points. For example, instead of a glassinsulating member, a synthetic resin may be used. The recess 19 intheupper side of the insulating member may be omitted. The plate may form apart of the grid; if desirable, it may also be omitted. The conductorsprojecting from the bottom preferably have the shape shown, in which thethickenings can abut against an aperturedl mounting panel. However, adifferent shape may also be' chosen.

FIG. 8 shows an embodiment of a part of a jig for the series productionof the base shown in FIGS. 4 to 6 namely in the position of filling themould, compare FIG. 1. The mould mainly comprises a closure plate 30, asealing block 31, and pressure members 32 which can be passed throughthe sealing block.

The sealing block is constituted by a graphite block in whichlongitudinal and transverse grooves are provided so that dams 36 areformed. The sealing block thus obtains the shape of a plate from whichthe dams 36 project. Between the dams 36, apertures 40 are present inthe sealing block 31 through which the pressure members 32 can bepassed. In order to obtain matrix cavities in which the glass can enterunder the pressure of the pressure members 32 without laterally flowingin the longitudinal and transverse grooves, cross beams 37 are securedin the transverse grooves and are provided with ridges 38. Centeringpins 42 may be provided on the ridges 38 which pins can cooperate withthe centering apertures 26 in the connection members of the conductorgrids, The chambers in which the bases are formed are denoted by 43.Slots 41 are present between the pressure members 32 and the dams 36(see FIG. 9) into which slots the ends of the conductors connected tothe frame can be inserted. The slots 41 leave only such a space betweenthe pressure members 42 and the dams 36 that during the pressure theglass is not forced into the slots so that a sealing at that area is notnecessary.

In order to obtain the base shown in FIGS. 4 to 6, the closure plate 30comprises bosses 45 which fall in the base caps (compare FIGS. 1 and 3)and against which the bent ends of the conductors engage. Bosses 46 arealso present which press against the metal plates which serve as asupport for the semiconductor elements.

It will be obvious that such a structurally comparatively simple mouldis particularly suitable for the simultaneous manufacture of a number ofbases. The way of manufacturing has already been described clearly forone base with reference to FIGS. 1 to 3. The mould enables the use of aseries of interconnected conductor grids which can be centered relativeto the cavities and which are flexible so that deformation of theconductors does not occur.

FIG. 10 shows a part of the sealing block of a second embodiment of themould. This mould is extremely simple in design. It consists preferablyof parts which are manufactured from graphite. The closure plate and thepressure members may be shaped in the same manner as in the embodimentshown in FIG. 8. The sealing block consists of longitudinal beams 54 andcross beams 55 which are connected together, The cross beams have ridges56 which may be provided again with a centering pin 57 for centering theconductor grids. The longitudinal beams 54 are situated each timebetween two ridges 56 so that the mutual position is preferably fixed.The parts of the cross beams 55 not provided with a ridge fall inrecesses 58 of the longitudinal beams so that their position is alsoperfectly fixed.

The pressure members and also the ridges again have such dimensions thata slot of a small thickness in which parts of the grid can fall isformed between the upright walls of the dams and the pressure membersand ridges, respectively.

The operation of this mould corresponds entirely to the operation of thejig shown in FIG. 8 so that this need not be further described herein.

What is claimed is:

1. A method for making a base for an electric component, comprising thesteps of:

forming conductive strips each having a transversely bent over portionnear one end thereof;

spacing the strips around a block of heat softenable insulating materialhaving a top surface, a bottom surface, and a side surface, each stripextending along the side surface to and beyond the bottom surface withthe bent over portion partially covering the top surface;

heating the block of insulating material until suitably soft;

while the block is soft, compressing the block between a first solidsurface covering the top surface of the block and a second surfacecovering the bottom surface of the block, whereby the bent over portionof each strip is pinched and held between the first surface and the topsurface of the block while soft insulating material from the side of theblock is squeezed through the spaces between the strips; and

along the side surface to and beyond the bottom surface with the bentover portion partially covering the top surface.

4. The method of claim 1 wherein the molding step includes maintainingthe position of the strips.

5. The method of claim 1 wherein the compressing step includesmaintaining the position of the strips.

6. The method of claim 1 wherein the insulating material is glass.

1. A method for making a base for an electric component, comprising thesteps of: forming conductive strips each having a transversely bent overportion near one end thereof; spacing the strips around a block of heatsoftenable insulating material having a top surface, a bottom surface,and a side surface, each strip extending along the side surface to andbeyond the bottom surface with the bent over portion partially coveringthe top surface; heating the block of insulating material until suitablysoft; while the block is soft, compressing the block between a firstsolid surface covering the top surface of the block and a second surfacecovering the bottom surface of the block, whereby the bent over portionof each strip is pinched and held between the first surface and the topsurface of the block while soft insulating material from the side of theblock is squeezed through the spaces between the strips; and molding toa suitable shape the soft insulating material which squeezes through thespaces between the strips.
 2. The method of claim 1 wherein the formingstep comprises forming a grid of parallel spaced conductive fingershaving a transversely bent over portion near one end thereof.
 3. Themethod of claim 2 wherein the spacing step comprises positioning thegrid adjacent a block of heat softenable insulating material having atop surface, a bottom surface, and a side surface, the grid extendingalong the side surface to and beyond the bottom surface with the bentover portion partially covering the top surface.
 4. The method of claim1 wherein the molding step includes maintaining the position of thestrips.
 5. The method of claim 1 wherein the compressing step includesmaintaining the position of the strips.
 6. The method of claim 1 whereinthe insulating material is glass.